A bone defect or damage has been treated with artificial bone.
Dense and porous calcium phosphate artificial bone has been conventionally known. Such artificial bone needs to be processed in shape to fit the state of bone to be treated. However, such artificial bone is hard to cut or shave in an operation site, and is therefore difficult to use.
For such problems, paste-like bone filling materials which are suspensions of calcium phosphate granules in an aqueous medium have been suggested (for example, Patent Literature documents 1 to 3). Such paste-like bone filling materials can be used to fill a bone defect or damage using an injector or the like. The paste-like bone filling materials cure after filling and fixed at the bone defect or damage. The use of the paste-like bone filling materials enables easy treatment of even a complicated bone defect or damage.
However, the paste-like bone filling materials described in Patent Literature documents 1 to 3 can only fill a bone defect or damage, but cannot promote bone regeneration. Actually, bone regeneration occurs only at the surface of a bone filling material used for filling. The bone filling materials have very high mechanical strength, but are poor in elasticity and toughness because they do not contain an organic component of bone tissues, such as collagen fibers. This is a fatal disadvantage of the material. For this reason, bone regeneration materials have been required to fill a bone defect or damage and secure the mechanical strength of the bone in the short term and promote regeneration of the patient's own bone in the long term.
For such problems, Patent Literature 4 discloses a bone regeneration material kit including particles comprising a calcium phosphate compound, particles comprising a bioabsorbable polymer, and an aqueous medium. When the bone regeneration material kit described in Patent Literature 4 is used to fill a bone defect or damage, bioabsorption of the particles comprising a bioabsorbable polymer occurs, and continuous pores generate in a filled portion. Osteoblastic cells enter the continuous pores and grow therein. That is, the bone regeneration material kit described in Patent Literature 4 can fill a bone defect, and further serve as a scaffold material for growth of osteoblastic cells.